Amazon Elastic MapReduce (Amazon EMR) is a web service that makes it easy to process large amounts of data using Hadoop on AWS. Amazon EMR now supports 4 new memory-optimized instances types: r3.xlarge, r3.2xlarge, r3.4xlarge, and r3.8xlarge. These instance types have the lowest cost per GiB of RAM among all Amazon EC2 instance types. They are ideal for applications like Impala and Spark that need large amounts of memory.

You can learn more about these instance types on the EC2 Instance Types page. To use these instance types with EMR, you must use AMI version 2.4.5 or later (for Hadoop 1) or AMI version 3.0.4 or later (for Hadoop 2).